In a process such as etching, deposition, oxidation, and sputtering in a manufacturing process of a semiconductor device or a FPD (Flat Panel Display), plasma has been widely used to carry out a sufficient reaction to a processing gas at a relatively low temperature. In such plasma processes, a high frequency power (RF) or a microwave power has been used to electrically discharge or ionize a processing gas within a vacuum processing chamber.
In a capacitively coupled plasma processing apparatus using a high frequency power (RF), an upper electrode and a lower electrode are arranged to be parallel with each other within a processing chamber, a target substrate (a semiconductor wafer, a glass substrate, or the like) is typically mounted on the lower electrode, and a high frequency power having a frequency (typically, about 13.56 MHz or more) suitable for plasma generation is applied to the upper electrode or the lower electrode. Due to a high frequency electric field generated between the two electrodes facing each other by applying the high frequency power, electrons are accelerated, and due to ionization by collision between the electrons and a processing gas, plasma is generated. Further, due to a gas phase reaction or a surface reaction of radicals or ions in the plasma, a thin film is deposited on the substrate, or a material of the substrate or a thin film on a surface of the substrate is etched.
Recently, as a technology of rapidly increasing performance in a capacitively coupled plasma processing apparatus, a technology of applying a negative DC (Direct Current) voltage to a facing electrode (typically, an upper electrode) that faces a substrate with a processing space therebetween has attracted attention (Patent Document 1). This upper electrode DC power applying manner has at least one of the following effects: (1) the effect of enhancing sputtering at the upper electrode by increasing an absolute value of a self-bias voltage of the upper electrode; (2) the effect of reducing generated plasma by expanding a plasma sheath at the upper electrode; (3) the effect of irradiating electrons generated near the upper electrode to the target substrate; (4) the effect of controlling a plasma potential; (5) the effect of increasing an electron density (plasma density); and (6) the effect of increasing a plasma density at a central portion thereof.